Circuit interrupter



Oct. 31, 1939.

T. G. A. s LERs CIRCUIT INTERRUPTER Filed Oct. 24, 1935 3 Sheets-Sheet l -Oct, 31, 1939. T. G. A. SILLERS 2. 78.110

OIRCUIT INTERRUPTER Filed Oct. 24, 1935 3 Sheets-Sheet 2 Patented Oct. 31, 1939 I UNlTED STATES PATENT orFicE Application October 24, 1935, Serial No. 46,474:

10 Claims.

This invention relates in general to circuit breakers and more particularly to circuit breakers of the fluid break type wherein the arc formed during interruption of the circuit is extinguished (in oii or some similar insulating and arc extinguishing iiuid.

It is an object of this nvention to provide in a` circuit breaker of the above type an improved .ethod of and means for extinguishing the arc and interruptng the circuit in an improved and more eicient rnanner.

.li-n circuit breakers of the prior art, ntilization oi the 'so-called explosion pot to aid in arc extinguishment, has brought about several probleme. 'Ifhe usual explosion pot includes an oil filled chamber provided with a fixed contact supported at one end thereoi and further provided. with a threat opening at the other end thereof, through which the movable contact operates, the threat providing for a region of turbulence into which the are is drawn and extinguished.

I One of the difiiculties enccuntered in the above type of circuit breaker is that if the pots are designed to properly withstand the pressure due to gas generation at high current values, that at low current values the gas generated will not cause suffcient turbulence to extinguish the arc which may become stabilized causing a falure of the circuit breaker. Various schemes have been i resorted to in order to obviate the above clifficulty,

one of which was that of designing the pot so as to maintain the desired pressure at low Currents and then prevent excessive pressure at high currents by the so-called top-venting, that is, a e relief opening or valve in the top of the pressure chamber.

Other methods of solving the above problem involve the use of additional devices such as deionizing grids, the use of one arc to blast a jet of oil across another arc, and means for breaking an arc into small arcs. The use of any additional device of courseadds to the eXpense and necessary maintenance and brings up unioreseen problens not present Without these devices.

Another method of solving the above problem is in using a small, very high pressure pot which is side 'ventcd through battles which break up the arc. To obtain the necessary high pressure the moving contact must fit very closely in the throat and the pot must necessarily be small.

Likewise the side vent must be restricted to obtain the necessary high pressure and of sufcient length to provide for cooling of the arc and aro products before permitting them to contact the 55; outside casing and rise above the fluid level; A

disadvantage of this type of circuit breaker is that it is necessarly designed to extinguish the arc before the moving contact moves through the throat opening. This means that ail the oil in the pot is used to create pressure and turbulence 5 and there is none left to provide the throat effect if the arc is drawn out of the pot, the break er then beconing in efiect, a plain break b'eal zer with an are length from contact tip to throat opening thereby causing breaker failure ii not blowing up of the circuit breaker.

It is therefore an object of the present invention to avoid any or all of the'above diicuties and at the same time obtain a greater range of safely handled currents and allow commercial tolerances between throat and moving contact.

It is also an object of the present invention to avoid the dificulties as above set forth and to provide a circuit breaker of the explosion pot type which will efciently interrupt Currents oi both` high and low values without necessitating the use of' additional devices.

Another object of the present invention is to provide a circuit breaker of the explosion pot type having a threat opening through which the moving contact operates, with an unrestricted expulsicn port immediately adjacent the separating Contacts.

It is another object of this invention to provide an expulsion port circuit breaker with a port the size of which varies in accordance with the amount of contact separation.

Objects and advantages other than those above set forth Will be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 is a vertical sectional View taken on the line I-I of Fig. 2 of a cirouit breaker embodying the present invention;

Fig. 2 is a horizontal sectional view of the circuit breaker of Fig. 1 taken along the line 'ii-II;

Fig. 3 is a vertical sectional View of a circuit breaker taken on the line III-III of Fig. 4 einbodyng a modified form of the present invention;

Fig. 4 is a horizontal sectional View of the circuit breaker shown in Fig. 3 taken along the line IV-IV;

Fig. 5 is a vertical sectional View of a circuit breaker taken along the line V-V of Flg. 6 embodying another modified form of the present invention;

Fig. 6 is a horizontal sectional View taken along the line VI-VI of the circuit breaker of Fig. 5;

Fig. '7 is a view of the circuit breaker of Figs. 5

and 6 showing another contact position thereof;

Fig. 8 is a vertical sectional View of a circuit breaker embodying another modification of the present invention;

Figs. 9 to 13 illustrate the insulating members utilized to make up the pot of the circuit breaker of Fig. 8.

In the embodiment of the invention as shown in Figs. 1 and 2 a pot !9 is shown immersed in oil or a similar fluid in a tank !5 and is supportecl in any conventional manner by means of the rod !8 and bushing ll. The pot !9 is made oi insulating material suitably molded or otherwise formed to provide a pressure chamber 22 and a vertical slotted vent 27. The cover member :lil of the pot is supported on the bushing structure by an enlarged head portion of the rod i@ which forms the fixed contact 24. The pot is suitably fastened to the cover member 30 by the cap screws 29. The pressure chamber 22 is divided vertically by partition members 23 and horizontally by partition members 25 which restrictthe free passage of gas and insulating liquid toward the throat 26 and direct them toward the slot 27. The moving contact 2l is mounted on the bridging member 20 and operates through the throat 23 to cooperate with the fixed contact 24; The tark !5 has an insulation lining !4 to prevent the stabilization of an arc from the said contacts to the tank 15.

Upon separation of the contacts 2! and 24 an arc is drawn. When these contacts are just slightly separated, the major portion of the vent 21 is operatively closed in that it is substantially blocked by the moving contact 21. The portion of the pressure chamber 22 above the top partition member 25 forms a small pressure chamber. As soon as the arc is drawn, the gas generated thereby has only one means of escape which is through the open portion of the vent 21 which forms the expulsion port. The expulsion port principle of arc extinction is fundamentally that of drawing an arc in a closed oil chamber with the only point of egress for the gases formed by the arc being an opening or port located immediately adjacent to the point of arcing. Under these conditions, as soon as the arc is struck, gas is formed which passing out through the port at high velocity results in a blast action and turbulence at the point of arcing which tends to disrupt the arc stream and shut ofi the conducting path during a zero point of the current wave.

In the ordinary explosion pot Where the deionizing action of the throat does not commence until considerable time after the arc is first drawn, a high pressure is built up during movement of the arcing tip to the throat. In the present invention due to the expulsion port being immediately adjacent the point of contact separation, the venting and arc extinguishing action can begin immediately and it is not necessary to hold a high pressure for a considerable period of time, thereby allowing a considerable saving in the necessary strength of the pot structure. Also in the ordinary pressure pot in order to have sufficient pressure for arc extinguishing at light currents, a means must be provided for avoiding excessive pressures at heavy currents. The present invention avoids the necessity for this added means.

The embodiment of the invention shown in Figs. 3 and 4 is similar to that above described but with an added venting chamber 34. The venting chamber 34 has the functions of pre- Venting deterioration and breakdown of the insulating wall 14 and that of preventing oil impact. Oil impact is the action of a solid slug of oil striking the underside of the top of the circuit breaker at a high velocity and is very objectionable as serious stresses are impa'ted by it to the circuit breaker structure, which tend to lift the circuit breaker from the floor. The impact further acts on the Operating mechanism tending to reclose the circuit breaker. By directing the oil from the pot downwardly through the vent 3l it must thereby pass through cool oil which reduces the temperature of the hot oil and gases and allows the energy thereof to become expended so that oil impact is decreased. Due to this reduction in temperature of the hot oil and gases, the dangers of secondary explosion of the gases which collect above the oil level |6 are thereby lessened. The venting chamber also has the function of providing a passage so that if the arc is looped outof the slot 27 it is still in a region of turbulence and deionization and is thereby extinguished. In as far as the expulsion port principle of operation is concerned, the circuit breaker of Fig. 3 operates similarly to that of Fig. 1. The partition members 23 and 25 of Figs. 1 and 2 may likewise be used in the embodiments of the invention shown in Figs. 3 to 8.

The circuit breaker shown in Figs. 5, 6 and '7 is a further modification of the invention above described. In this embodiment the pressure chamber is further sealed to provide for expulsion of the arc and arc gases only at a point adjacent the arc. The moving contact 'Zi supports a key 33 rigidly connected thereto and movable therewith which provides a closure member for the vent 21 except for that portion immediately opposite the space between the separated contacts. The circuit breakers previously described are designed so that the circuit may be broken and the arc extinguished prior to the time the moving contact 2! is withdrawn from the pot !9, however, if an arc should be drawn for the full length of the pot 19, the deionizing action of the throat 24 will then become effective. In the present embodiment provision is made for substantially sealing the pot IS along the moving contact 2I by having the same set closely in the extension 36. A stop member 4!! is provided which prevents the member 2| from being withdrawn from the pot I 9. A suitable basing means such as the spring 39 is provided to bias the contact 21 into the open position. For added safety and for isolation purposes a second break is formed between the head 31 of the moving contact 2! and a stub H carried by the bridging members 20.

In Fig. 7 the relationship of the parts is shown at the position shortly after the contacts are separated and an arc is drawn. As shown in this figure the gas bubble 43 generated by the arc 42 expands at a very high rate and can escape from the pressure chamber 22 only through the expulsion port, that is, that portion of the vent 21 not closed by the key 33. Expulsion of the gas and vaporized oil begins immediately upon formation of the arc for due to the fact that the expulsion port is immediately adjacent the arc, there is not the inertia of a mass of oil in the chamber to be overcome before expulsion can begin. A venting chamber may also be utilized with this modification.

In Fig. 8 a circuit breaker embodying the principles of the present invention is shown which may be made up from laminated insulation mem- 's bers such as shown in Figs. 9 and 13. The supporting rod i& is insulated in any well known manneras by the insulator' l'l and supports a conducting member i& which is threaded thereon. The member 18 has a cover member !19 suitably fastened thereto to which is fastened a metal shell usually of non-magnetic material which forms the explosion pot. Also carried by the member t is the fixed contact assembly 58, which is of any desired construction such as the several radially contact members flit which are connected to the conductor member l& by a jumper 55. The contact assembly 58 is astened to the conducting member te by means of a flange member ti' suitably bolted thereto.

On the outer pe'riphery of the member lil is a collar t l which serves as a stop member for the insulation members t. Below the members 9 are two members lil and a member il having portions thereof removed, thue forming the expulsion port se immediately adjacent the fixed contact. Situated below the member i l are members !2 forming the pressure chamber 22 the venting chamber er. At several places in chamber are members lt which have cutouts for the chamber tii and openings 535 for the moving contact member 25. The pot is closed by an insulation member 59 suitably flanged to fit on to a fiange at the lower end of the pot 52. The throat opening in member and throat 55 are designed to fit the contact member with commercial clearances so as to provide a substantially closed pressure chamber. The venting chamber 62, the shunt lil and the deflecting member 63 provide a means for freely ventng the arc and arc gases and for at the same tirne preventin'g oil impact and secondary explosions as described in regard to the breaker of 3. A. ring member E@ of insulation further insulates the pot 52 and is held in place by cap screws &9. The outside of the pot insulated by a tube of insulation 53 which is suitably fastened to the pot by means of screws El. The member se of insulatng material is used to prevent an arc which may lcop out into the venting chamber 62 :from becoming stabilized therethrough from the fixed contact to the moving contact when withdrawn from the pot.

When the contacts zl and are first separated and an arc is drawn, the expulsion port action on the arc and the arc gases is similar to that previously described in connection with the circuit breaker of Fig. 7. i However, as the movable contact 25 is drawn downwardly and a longer arc is drawn, the gas generated must travel along the path of the arc in order to vent out of the expulsion port Gili. It is obvious that the desired turbulence and deionization is to be had at the place where it is most necessary, that is, where the arc is. Upon breaking lighter currents a longer arc is drawn and the restricted portions 63 are utilized to obtain further areas of deionization and turbulence. Although this circuit breaker is designed to cause -arc extinction prior to movement of the contact 2! out of the pot, an added safety feature is provided in the throat 25. The chamber 22 is designed large enough to hold more than the amount of oil that will be vaporized during normal movement of the contact E l. Therefore, if an arc is drawn into the throat 26, there is suficient oil to be vaporsed so as to obtain the throat action of the throat 25 in turbulence and deionization so that the arc is extinguished.

It is thus apparent that we have shown and disclosed a circut breaker of the explosion pot type in which the throat or port has been moved to the position of maximum efficiency, that is, immediately adjacent the separating Contacts. Further, the aperture for the moving contact is utilized as a safety feature, which not only provides that the breaker may be safely utilized over a much greater range of Currents, but also that blowing up of the breaker at high currents and failure at low currents is prevented.

Although the throat or port has been moved to the position of maximum efficiency, the reserve supply of oil is maintained in the pressure chamber where it is readily available for deionization and turbulence. Further, the reserve supply of oil is in a free body rather than in small pockets or in the pores of material lining the arc path and the moving contact is moved positively through this reserve supply of oil rather than depending upon magnetic action to bring the arc in contact with this reserve supply of oil. Due to the fact that cooling and prevcntion of explosion and impact are provided for by the venting chamber, a short unrestricted port can be used and hence the pressure necessary to obtain the desired turl'ulence deionization is greatly reduced. Due to the low internal pressure the clearances between moving contact and throat may be within commercial tolerances and the pot structure may be more cheaply and simply constructed.

Although in the specific embodiments shown in the drawings, a liquid has been indicated as the arc ertinguishing medium, any of the well shown gases may be utilized, for example, compressed air It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the invention illustrated and described without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In combination, a casing containing arc extinguishing fluid, a pot structure in said fluid provided with a pressure chamber and a venting chamber therein, a short expulsion port connecting said chambers, a fixed contact in said pressure chamber, and a movable contact normally substantially closng said pressure chamber except through said port and cooperatng with said fixed contact to draw an arc in said fluid immediately adjacent said port.

2. A circuit brealer comprsing a casing containing arc extinguishing fluid, a pot structure in said fluid provided with a pressure chamber therein, a fixed contact in said chamber, an opening in said chamber, means comprising a movable contact withdrawable from said chamber through said opening for normally closing said opening during circuit interruption, said movable contact cooperating with said. movable contact to draw an arc therebetween, means comprising a second opening in said chamber for expelling said arc and arc gases therefrom at a point immediately adjacent the inception of said arc, and means commising a second chamber in said pot providing free venting and cooling of said arc and arc gases prior to movement thereof into said casing.

3. A circuit breaker comprising a casing containing arc extinguishing fluid to a given level, a pot structure in said fluid provided with a pressure chamber therein, a first contact in said chamber, an opening in said chamber, means comprising a movable contact withdrawable from said chamber through said opening for normally closing said opening during circuit interruption, said movable contact cooperatng with said first contact to draw an arc therebetween, means comprising a second opening in said chamber at the point of separation of said contacts providing unrestricted lateral venting of the gas generated and the fluid disassociated 'by said arc, and means directing said gas and fluid in a direction downwardly from said level of said fluid in said casing.

4. A circuit breaker comprising a casing containing arc extingushng fluid, a pot structure having a pressure chamber therein providing a reserve supply oi' said fluid, a fixed contact in said chamber, an opening in said chamber, means comprising a movable contact withdrawable through said reserve fluid and through said opening for normally closing said opening during circuit interruption, said movable contact cooperating with said fixed contact to draw an arc therebetween, a lateral vent immediately adjacent said separating contacts, means comprising a venting chamber in said pot for directng the flow of gas and fluid vented from said pressure chamber in the direction of circuit opening movement of said movable contacts, and means for directing the flow of gas and fluid vented from said venting chamber away from said movable contact member.

5. In combination, a substantially cylindrical pressure pot provided with arc extinguishing fluid therein, a fixed contact in said pot, a contact movable longitudinally through the bottom of said pot centrally thereof and cooperable with said fixed contact to draw an arc therebetween, a semi-oylindrical pressure chamber in said pot, a narrow lateral vent in said pot immediately adjacent the line of separation of said contacts, and means for uncovering said vent proportionally to contact separation, said means comprising a closure member in said vent carried by said movable contact.

6. A circuit breaker comprising a tank containing arc extinguishing fluid to a given level, a pot immersed in said fluid, a pressure chamber in said pot, a fixed contact supported in said g pressure chamber, a movable contact cooperable with said fixed contact to draw an arc therebetween and withdrawable from said pressure chamber through a throat the'ein to provide a region of deionization and turbulence, a venting chamber in said pot, a lateral expulsion port providing communication from said pressure chamber to said venting chamber at a point immediately adjacent said separatng contacts, means for venting said venting chamber in a direction away from the level of said fluid in said tank and away from said movable contact.

7. A circuit interrupter comprising a tank containing arc extingushing fluid, a pot formed of insulating material supported therein, a narrow lateral vent in said pot, a fixed contact mounted in said pot adjacent one end of said vent, a contact movable through the opposite end of said pot immediately adjacent the inner edge of said vent and cooperable with said fixed contact to draw a circuit breaking arc the'ealong, and a key mounted on said moving contact and slidable in said vent.

8. In combination, a pot formed of insulating material and provided with insulating and arc extinguishing fluid therein, a slot in the side wall of said pot, a contact carried in said pot adjacent one end of said slot, a second contact movable through the opposite end of said pot adjacent said slot, and a closure member in said slot carried by said second contact.

9. In combination, a pot formed of insulating material and provided With insulating and arc extinguishing fluid therein, a slot in the side wall of said pot, a contact carried in said pot adjacent one end of said slot, a second contact movable through the opposite end of said pot adjacent said slot, a key carried by said second contact and movable in said slot, and an isolating contact cooperating with said second contact.

10. In a circuit interrupter, means deflning an arc chamber, a stationary contact in said chamber, a contact carrying member having a movable contact thereon adapted to be moved by said member into and out of engagement With said stationary contact, means along the walls of said chamber which gives off a gas when acted upon by an arc to aid in the extinguishing of an arc, means comprising a vent in said arc chamber providing for the escape of fluid therefrom, said contact carrying member being disposed in said chamber to substantially cover said vent when the member is in the closed circuit position, and means for moving said contact carrying member to establish an arc between said contacts and to uncover said vent in proportion to contact movement, said means comprising a closure member in said vent carried by said contact carrying member.

THOMAS G. A. SILLERS. 

